This article describes the newest achievements in the heat treatment of diesel-engine fuel-injection nozzles made of hot-working tool steel. Different methods of improving surface properties have been applied by means of vacuum carburizing and vacuum nitriding, which is especially suitable for elements characterized by difficult shape geometry such as blind holes. Variable process parameters have been considered in terms of sequence and temperature as well as their influence on surface microstructure, hardness and case-layer uniformity.

Heating of loads in modern plasma nitriding furnaces is carried out by a combination of the radiative heat transfer from the wall or furnace resistance heaters and heat transfer from the glow discharge. We will look at the effect of the workpiece emittance on its temperature.

Hardenability is the ability of steel to partially or completely transform from austenite to some fraction of martensite at a given depth below the surface when cooled under a certain condition. The “gold standard” test for all hardenability results has always been the “Jominy End-Quench Test.”